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As Loran Fades, Attention Shifts to DGPS and SBAS

November 30, 2009 - By

Few precise-positioning users have employed Loran in a professional sense, although maybe you have in your personal life if you’re a airplane pilot or a mariner. Then again, if you've flown as an airline passenger or cruised onboard a ship, you've benefited from the back-up to GPS that Loran provides. That back-up is about to go away. As attention and resources shift away from Loran, they focuses more intensely on GPS augmentations, specifically differential GPS (DGPS) and satellite-based augmentation systems (SBAS) such as WAAS and EGNOS. read more

This article is tagged with and posted in Newsletter Editorials, Opinions, Survey, Survey Scene

A Little Q&A Follow-up and Feedback on My Last Column

November 19, 2009 - By

I received some feedback on my last column entitled "What’s the Difference Between a Used Car Salesman and a GPS Salesman?" Most of the comments were positive in that the technical content was reasonably deep and thorough. However, I did receive a couple of e-mails from folks who were offended by the comparison. read more

This article is tagged with and posted in Newsletter Editorials, Opinions, Survey, Survey Scene

What’s the Difference between a Used Car Salesman and a GPS Salesman?

November 3, 2009 - By

I didn’t attend the Minnesota GIS/LIS Annual Conference last week, but I received a report from someone who attended a session in which the presenter seemed to fit the maxim quite well. One of the presenter’s messages was that people should stop using WAAS immediately as a GPS correction source due to the inability of data collection software to handle the ITRF00 > NAD83/CORS96 datum shift. Following is a statement from one of his slides… read more

This article is tagged with and posted in Newsletter Editorials, Opinions, Survey, Survey Scene

The System: Galileo Slips, EGNOS Operates

November 1, 2009 - By

Four Galileo in-orbit validation (IOV) satellites scheduled to launch next year have already missed their first pad date.The European version of Russia’s Soyuz rocket is now scheduled to carry the four IOV satellites into orbit in two launches in November 2010 and early 2011, as announced by European Space Agency (ESA) Director-General Jean-Jacques Dordain on October 9. Both launches had... read more

Innovation: Improving Dilution of Precision

November 1, 2009 - By

A Companion Measure of Systematic Effects
GPS receivers must deal with measurements and models that have some degree of error, which gets propagated into the position solution. If the errors are systematically different for the different simultaneous pseudoranges, as is typically the case when trying to correct for ionospheric and tropospheric effects, these errors propagate into the receiver solution in a way that is fundamentally different from the way that random errors propagate. So in addition to dilution of precision, we need a companion measure of systematic effects. In this month’s column, we introduce just such a measure. read more

This article is tagged with and posted in Algorithms & Methods, Innovation